Sulfur-containing compounds have been found in a wide range of foods and botanical essential oils. It is known that sulfur-containing compounds, which generally have extremely low threshold values, are perceived as an unpleasant odor at high concentrations, but give a characteristic aroma, such as a fruity note, at low concentrations and thus are important as an aromatic component.
For example, Patent Literature 1 discloses ethyl 3-mercaptobutyrate as a flavoring agent. Patent Literature 2 discloses ethyl 3-mercaptohexanoate. Further, Patent Literature 3 discloses ethyl 4-thioacetoxybutyrate.
As a method for producing such sulfur-containing compounds, for example, Non Patent Literature 1 describes an overnight reaction of ethyl crotonate with thioacetic acid at 150° C., which gave ethyl 3-acetylthiobutanoate at a yield of 54%. Non Patent Literature 2 describes a reaction of ethyl 2-ethyl-2-propenoate with thioacetic acid (2 Eq), the reaction being performed at 65° C. for 36 hours.
Patent Literature 4 discloses synthesis of ethyl 3-mercapto-2-methylpropionate and ethyl 3-acetylthio-2-methylpropionate by an addition reaction of thioacetic acid to ethyl 2-methyl-2-propenoate. Patent Literature 1 describes production of a compound having a mercapto group by reduction of a disulfide compound obtainable by a reaction of ethyl crotonate with sodium hydrosulfide.